China disputed claims Tuesday about inadequate efforts to save the crew of tanker Sanchi, saying they are “untrue and irresponsible.”

Foreign Ministry spokesperson Lu Kang said at a daily press briefing that China mobilized nine vessels on the day the accident happened and there had been more than 13 rescue vessels at the scene from the second day.

Rescue forces from Shanghai and Jiangsu worked with Japan and the Republic of Korea (ROK) in the rescue operations, said Lu.

An Iranian Foreign Ministry spokesperson said Monday that it is “not true” to say that China had not made adequate efforts when faced with such a complex accident and that China had provided the utmost cooperation to Iran during the process.

“The remarks from the Iranian side shows that claims of an inadequate rescue are untrue and irresponsible,” said Lu.

The Panama-registered oil tanker Sanchi, carrying 136,000 tonnes of light crude oil from Iran, collided with the CF Crystal, a Hong Kong-registered bulk freighter, about 300 kilometers east of the Yangtze estuary on Jan. 6. Thirty-two crew members of the tanker, 30 Iranians and two Bangladeshis, were lost.

The entire ship sank Sunday afternoon. No burning was seen on sea surface from a marine surveillance plane at about 1 p.m. Monday and the oil spill could be easily seen from the air.

Lu said China welcomes Iran to join in the investigation of the accident, and will facilitate visas for the families of the crew.